Inorg. Chem. 1993,32, 1662-1670
1662
Mixed Transition Metal-Main Group Atom Clusters as Potential Models for M2X (010) and M4 (100) Surfaces. Synthesis and Spectroscopic and Structural Characterization of M4(CO)&3-PPh) (M = Ru, Os). Pyramidal Clusters with M3P Square Faces Andrew A. Cherkas, John F. Corrigan, Simon Doherty, Shane A. MacLaughlin, Franqoise van Gastel, Nicholas J. Taylor, and Arthur J. Carty’ Guelph-Waterloo Centre for Graduate Work in Chemistry, Waterloo Campus, Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N 2 L 3G 1 Received October 9. 1992 Theclusters HM3(CO)&-PPhz) (M = R u (la), Os (lb)) areshown to beconvenient precursorsofthephosphinidenestabilized clusters nid0-M,(CO)~3(p3-PPh) ( M = Ru (2a),Os (2b))via P-C(Ph) activation, reductive elimination of benzene, and condensation. Heating a toluene solution of la under a purge of carbon monoxide forms R u ~ ( C O ) I ~ ( ~ ~ PPh) (40%) as the major product. Formation of O S ~ ( C O ) ~ ~ ( ~requires ~ - P P more ~ ) forcing conditions. Heating a solid sample of lb at 215 OC for 8 min affords 2b in 2@ 25% yield. Both 2a and 2b have been characterized by spectroscopy and by accurate single-crystal X-ray structure analyses. Crystals of 2a and 2b are isomorphous, crystallizing in the orthorhombic space group P212121 with the following unit cell dimensions: 2a,u = 11.031(2), b = 12.366(2), and c = 18.094 A, with 2 = 4;2b,u = 11.055(3), b = 12.344(3), and c = 18.016(5) A, with 2 = 4. The molecular structures of 2a and 2b possess M4P cluster frameworks containing a butterfly arrangement of metal atoms stabilized by a p3-phosphinidene fragment capping an open triangular face. Both clusters adhere to the effective atomic number rule (62 electrons) and are associated with nido octahedral M4P core geometries when the skeletal bonding electrons are considered (seven skeletal electron pairs, five vertices). In the latter instance the “PPh” fragment is located in the square basal planeof the pyramidal framework. An alternative, less time-consuming procedure for the preparation of R U ~ ( C O ) I ~ ( ~ ~(2s) - P is P ~also ) described. Dropwise addition of dichlorophenylphosphine toa concentrated T H F solution of thedianion K2[Ru4(CO) affords 2a in reasonable yields. Variabletemperature 13C N M R studies of 2a revealed four independent dynamic processes involving localized CO exchange, and a direct comparison is drawn between 2a and (p-H)2R~4(C0)1~(p3-PPh). At temperatures in excess of 296 K, we have observed the onset of total intermetallic C O scrambling. The potential of clusters 2a and 2b to serve as molecular models for catalytically active transition metal and transition metal-main group surfaces as well as potential precursors to square planar metal clusters stabilized by p4-phosphinidene ligands are discussed.
Introduction The activation of small molecules at a polymetallic center and the modeling of molecular interactions at metal and metal-nonmetal surfaces are major incentives for the continued development of metal-cluster chemistry.’ Recent studies in the latter area include the characterization of benzyne-coordinated tetra- and pentaruthenium clusters as molecular models for the dissociative chemisorption of benzene at a stepped catalytically active site on a metal (1 11) surface,2 while the nondissociative chemisorption of benzene at a 3-fold site on the surface of a close-packed lattice has been mimicked by the cluster [Os3(CO)s(p,-92:112:t12.CsHg)l .3 The development of such models remains fundamental to our understanding of surface chemistry at the molecular level, and since the formulation of the cluster-surface analogy by Muetterties4and others,5 this approach has been utilized extensively.6 In principle, there exists an extensive array of clusters of differing (a) Humphries, A. P.; Kaesz, H. D. Prog. Inorg. Chem. 1979, 25, 145. (b) Davies, S. C.; Kablunde, K. J. Chem. Rev. 1982,82, 153. (c) Arif, A. M.; Bright, T. A.; Jones, R. A.;Nunn, C. M. J.Am. Chem. SOC.1988, 110,5389. (d) Adams, R. D.; Horvath, I. T. Prog. Inorg. Chem. 1986, 73,126. (e) Raithby, P. R.; Rosales, M. J. Ado. Inorg. Chem.Radiochem. 1985.29.169. (0 Sappa, E.; Tiripicchio, A.; Braunstein, P. Chem. Rev. 1983, 83, 203. (g) Amoroso, A. J.; Gade, L. H.; Johnson, B. F. G.; Lewis, J.; Raithby, P. R.; Wong, W. T. Angew. Chem., Int. Ed. Engl. 1991, 30, 107.
(a) Knox, S. A. R.; Lloyd, B. R.; Orpen, A. G.; Vinas, J. M.; Weber, M. J. Chem. SOC.,Chem. Commun. 1987, 1498. (b) Knox, S. A. R.; Lloyd, B. R.; Morton, D. A. V.; Nicholls, S. M.; Orpen, A. G.; Vinas, J. M.; Weber, M.; Williams,G. K. J. Organomet. Chem. 1990,394,385. (a) Johnson, B. F. G.; Lewis, J.; Gallup, M.; Martinelli, M. Discuss. Faraday SOC.1991, 92, 241. (b) Gallop, M. A.; Gomez-Sal, M. P.; Housecroft, C. E.; Johnson, B. F. G.; Lewis, J.; Owen, S. M.; Raithby, P. R.; Wright, A. H. J. Am. Chem. SOC.1992, 114, 2502.
nuclearities available for surface modeling studies ranging from the metal-metal-bonded dimer7to clusters with ten or more metal atoms often structurally comparable to a fragment of the bulk metallic latticee8 However, for reasons of simplicity and ready availability, by far the most widely used cluster types are those containing three mutually bonded metal atoms which mimic a 3-foldsiteinaclosepackedarrayofmetalat0ms.~~~ Thedominant obstacle to the use of high-nuclearity clusters remains their inaccessibility (in workable quantities) by conventional synthetic
route^.^ The butterfly cluster arrangement of metal atoms has attracted (4) (a) Muetterties, E. L. Angew. Chem., Int. Ed. Engl. 1978, 17, 545. (b)
Muetterties, E. L.; Rhodin, T. N.; Band, E.; Brucker, C. F.; Pretzer, W. Chem. Rev. 1979, 79, 91. (c) Muetterties, E. L. Pure Appl. Chem. 1982, 54, 83. (d) Muetterties, E. L. Chem. SOC.Reo. 1982, 283. (e) Muetterties, E. L.; Krause, M. J. Angew. Chem., Int. Ed. Engl. 1983,
22, 135. (5) (a) Evans, J. Chem. SOC.Rev. 1981, I O , 159. (b) Somorjai,G. A. Chem. SOC.Rev. 1983,321. (c) Ertl, G. In Metal Clusters in Catalysis; Gates, B. C., Guczi, J., Knozinger, H., Eds.; Elsevier: Amsterdam, 1986. (d) Braunstein, P. Nouu. J. Chim. 1986, I O , 365. (e) Wadepohl, H. Angew Chem., Int. Ed. Engl. 1992, 31, 247. (6) Weigand, B. C.; Freind, C. M. Chem. Rev. 1992, 92, 491. (7) Riera, V.; Ruiz, M. A.; Villafane, F. Organometallics 1992, 11, 2854. (b) Chini, P. J. Organomet. Chem. 1980, 29, 1. (c) Muetterties, E. L.; Stein, J. Chem. Rev. 1979, 79, 479.
(8) (a) Albano, V. G.; Ceriotti, A.; Chini, P.; Ciani, G.; Martinengo, S.; Naker, M. J. Chem. Soc., Chem. Commun., 1975, 859. (b) Jackson, P. F.; Johnson, B. F. G.; Lewis, J.; Nelson, W. J. H.; McPartlin, M. J. Chem. SOC.,Dalton Trans. 1982, 2099. (c) Ciani, G.; Sironi, A.; Martinengo, S. J. Chem. Soc.. Dalton Trans. 1982, 1099. (d) Martinengo, S.; Ciani, G.; Sironi, A. J. Am. Chem. SOC.1980, 102, 7565. (e) Chini, P. J . Organomet. Chem. 1980, 200, 37. (9) Bantel, H.; Hansert, B.; Powell, A. K.; Vahrenkamp, H. Angew. Chem., Int. Ed. Engl. 1989, 28, 1059.
0020-166919311332-1662$04.00/0 0 1993 American Chemical Society
Transition Metal-Main Group Clusters
Inorganic Chemistry, Vol. 32, No. 9, 1993 1663
considerable attention,1° a consequence of both its structural and electronicversatility." We12and other^^^,'^ have recognized the potential of these M4 frameworks (dihedral angles 90-180°) to serve as models for the chemisorption of small unsaturated molecules and for C-X bond forming/cleavage reactionsoccurring at a stepped catalytically active site on a metal surface. In addition to the close resemblance of the geometrical arrangement of metal atoms in nido-Ru4(CO) 13(~3-PPh)to a stepped metal surface, its main groupmetal atom framework (M3P square face) bears a remarkably close similarity to the atomic connectivity of ruthenium and phosphorus in ruthenium phosphide, RuzP (O10).14 The chemistry of M4 clusters and their applications as models remain less well developed than those for their M3 counterparts in part due to the lack of rational synthetic procedures coupled with facile fragmentation pathways often observed for unsupported metal atom frameworks. Herein we report the synthesis and spectroscopic and structural characterization of two phosphinidene-stabilized clusters M 4 ( C O ) l&-PPh) (M = Ru (2a), Os (2b)) as potential models for metal and metal-main group atom surfaces. Clusters 2a and 2b have proven to be remarkably stable to fragmentation under a variety of c o n d i t i o n ~ . ~We ~J~ also note that the skeletal rearrangement of the M4-butterfly skeleton to a square M4 array offers an extension to further models (ruthenium (100)).
Experimental Section General Procedures. Standard double-manifold vacuum-line techniques were used for chemical manipulations, and all reactions were performed under an atmosphereof dry dinitrogen unless otherwise stated. All solvents were dried prior to use, hexane and tetrahydrofuran over sodium/benzophenone, dichloromethane and acetonitrile over P205, and xylenes and toluene over LiAlH4. Reactions were monitored by IR spectroscopy and thin-layer chromatography (Baker Flex, silica gel, 1B-F). Product purification was performed either by column chromatography (330 X 30 mm) with silica gel (70-230 mesh) or by thin-layer chromatography on silica gel plates (20 X 20 cm, Merck, TLC grade, Aldrich Chemical Co.). Solution infrared spectra were recorded on a Nicolet-520 FTIR spectrometer using sodium chloride cells. N M R spectra were recorded on Bruker AM-250 and AC-200 instruments, and chemical shifts were referenced internally to the solvents CD2Cl2 and CDCl3 (IH and I3C(lH)) and externally to 85% H3P04 (31P(lH)). Microanalyses were performed by Guelph Chemical Laboratories Guelph, Ontario. All chemicals were obtained from commercial sources and used without further purification with the exceptiom of trimethylamine oxide, which was freshly sublimed under vacuum (60 OC, 0.05 Torr, 16 h) prior to use.16a ~
~~
~
(10) (a) Sappa, E.; Tiripicchio, A.; Carty, A. J.; Toogood, G. E. Prog. Inorg. Chem. 1987, 35, 437. (b) Steinmetz, G. R.; Harley, D. A.; Geoffroy, G. L. Inorg. Chem. 1980, 19,2985. (c) Braga, D.; Johnson, B. F. G.; Lewis, J.; Mace, J. M.;McPartlin, M.; Puga, J.; Nelson, W. J. H.; Raithby, P. R.; Whitmire, K. H. J . Chem. Soc., Chem. Commun. 1982, 1082. (1 1) (a) Carty, A. J.; MacLaughlin, S. A.; Van Wagner, J.; Taylor, N. J. Organometallics 1982,1,1013. (b) Churchil1,M. R.;Bueno,C.;Young, D. A. J. Organomet. Chem. 1981, 139. (c) Hogarth, G.; Phillips, J. A,; van Gastel, F.; Taylor, N. J.; Marder, T. B.; Carty, A. J. J . Chem. Soc., Chem. Commun. 1988,1570. (d) Harris, S.; Blohm, M. L.; Gladfelter, W. L. Inorg. Chem. 1989, 28, 2290. (12) Corrigan, J. F.; Doherty, S.;Taylor, N. J.; Carty, A. J. Organometallics, in press. (13) (a) Osella, D.; Ravera, M.; Nervi, C.; Housecroft, C. E.; Raithby, P. R.; Zanelo, P.; Laschi, F. Organometallics 1991, 10, 3253. (b) Rossi, S.; Pursiainen, J.; Pakkanen, T. A. Organometallics 1991, IO, 1390. (c) Rumin, R.; Robin, F.; Petillon, F. Y.;Muir, K. W.; Stevenson, I. Organometallics 1991, 10, 2274. (14) (a) Rundqvist, S . Acta Chem. Scand. 1960,14, 1961. (b) Corbridge, D. E. C. In TheStructural Chemistry of Phosphorus; Elsevier Scientific Publishing Co.: Amsterdam, 1974, Chapter 3. (15) Corrigan, J. F.; Doherty, S.; Taylor, N. J.; Carty, A. J. J. Chem. SOC., Chem. Commun. 1991, 1640. (16) (a) Nicholls, J. N.; Vargas, M. D. Inorg. Synth. 1989, 26, 289. (b) Colbran, S. B.; Johnson, B. F. G.; Lewis, J.; Sorrell, R. M. J. Organomer. Chem. 1985, 296, C1.
The clusters (p-H)Rua(CO)lo(p-PPh2) (la)," (p-H)Os,(CO)&PPh2) (lb),I6and K ~ [ R U ~ ( C O were ) I ~ prepared ]~~ by standardliterature procedures. Preparation of Ruc(CO)13(pp-PPh) ( 2 4 . Heating a solution of la (3.54 g, 4.6 mmol) in toluene (150 mL) at reflux purged with a steady stream of CO gas resulted in the formation of a deep purple homogeneous solution. Thin-layer chromatography and I R analysis were used to maximize the formation of 2a. Reflux was maintained for 150 min. The resultingsolution was cooled to room temperature and the solvent removed invacuotoleaveanoilyresidue. Thisresiduewasdissolvedin theminimum volume of dichloromethane (10-12 mL); the solution was absorbed onto silica gel, desolvated, placed on a 330 X 30 mm silica gel column and eluted with hexane to afford seven well-separated bands. The first yellow band to elute was identified as R u ~ ( C O ) I Zthe , second red/purple band as Ru4(CO)&-PPh) (1.04 g, 1.2 mmol, 34%), and the third green fraction as R U ~ ( C O ) I ~ ( ~ ~ - PThe P ~next ) . ' ~fraction contained a mixture R U ~ ( C O ) & - P P ~followed ~)~~~ of yellow (p-H)2Rua(CO)s(p-PPh2)~~~and by (p3-H)R~5(CO)ln(pr-PPh)(p-PPhz).~~ The remaining two fractions, deep green followed by dark brown, have previously been characterized reas R u ~ ( C O ) I ~ ( P ~ -and P P Rus(C0)21(ps-P)014-PPh)(p-PPh2),2~ ~)~~~ spectively. The identity of these slower moving fractions was established by comparing their spectroscopicproperties with those previously reported. Crystals of 2a were obtained by cooling a dichloromethane/bcnzene mixture at -20 OC overnight. Anal. Calcd for C I ~ H S O I ~ P RC, U26.03; ~ : H,0.57. Found: C, 25.99; H , 0.70. IR (v(CO), cm-l, C6H12): 2097 (w), 2062 (vs), 2050 (s), 2042 (s), 2022 (w), 2012 (m), 1990 (w), 1969 (w, sh). 3LP(1H)N M R (101.3 MHz, CDClo, a): 409.0 (s). InC('H) N M R (62.0 MHz, CD2C12, 196 K, 6): 205.2 (d, CO, 2Jpc= 70.4 Hz), 200.7 (d, CO, 2Jpc 13.3 Hz), 197.8 (d, CO, 2Jpc = 5.0 Hz), 195.8 (s, CO), 191.7 (s, CO), 191.1 (d, CO, 2Jpc= 4.4 Hz), 187.8 (d, CO, 2Jpc 9.5 Hz), 184.9 (d, CO, ZJpc = 5.0 Hz), 150.9 (d, C ipso, lJpc = 12.9 Hz), 130.4 (d, C ortho, 2Jpc = 11.1 Hz), 130.4 (s, C para), 128.0 (d, C meta, 3 J= ~ 9.6 Hz). IH N M R (250.0 MHz, CDClo, 6): 8.0 (m, C a s , 2H), 7.2 (m, C a s , 3H). Preparation of Osr(CO)13(po-PPh) (2b). An evacuated Schlenk tube containing solid (p-H)Osa(CO)1o(p-PPh2) (lb) (0.158 g, 0.15 mmol) was heated in an oven at 215 OC for 8 min, during which the orange crystalline material melted to leave a dark brown solid residue upon cooling to room temperature. Extraction into dichloromethane followed by thin-layer chromatography (eluant: dichloromethane/hexane, 2030 v/v) afforded two major products. The first band to elute was initially identified as deep red Osr(C0) l&-PPh), subsequently confirmed by single-crystal X-ray analysis. Crystals of 2b were obtained from a dichloromethane/hexane solution at -20 OC (0.025 g, 21%). A deep yellow/orange band following 2b was identified as (p-H)2Osa(C0)9(P(Ph)C6H4) by comparison of its spectroscopic properties with those previously d e s ~ r i b e d . ~ ~ Anal. CalcdforC19H50130~4P:C, 18.51;H,0.41. Found: C, 18.21; H, 0.38. IR (v(CO), cm-I, c6H12): 2100 (m), 2066 (m, sh), 2060 (vs), 2053 (s), 2043 (s), 2033 (w), 2022 (w), 2014 (w), 2005 (s), 1992 (w), 1978 (w). 31P(LH)N M R (101.3 MHz, CDC13,b): 191.1 (s). "CIIH) N M R (50.3 MHz, CDCla, 298 K, 6): 178.7 (d, CO, 2Jpc = 5.0 Hz), 172.3 (s, CO), 162.1 (d, CO, 2 J= ~ 16.0 Hz), 140.0 (d, C ipso, lJpc = (17) Nucciarone, D.; MacLaughlin, S. A.; Carty, A. J. Inorg. Synth. 1989, 26, 264. (18) Bhattacharyya, A. A.; Nagel, C. C.; Shore, S.G. Organometallics 1983, 2, 1187. (19) Natarajan, K.; Zsolnai, L.; Huttner, G. J. Organomet. Chem. 1981, 209, 85. (20) Patel, V. D.; Cherkas, A. A.; Nucciarone, D.; Taylor, N. J.; Carty, A. J. Organometallics 1986, 5, 1498. (21) (a) Bruce, M. I.; Shaw, G.; Stone, F. G. A. J. Chem. SOC.,Dalton Trans. 1972, 2094. (b) Rosen, R. D.; Geoffroy, G. L.; Bueno, C.; Churchill, M. R.; Ortega, R. B. J. Organomet. Chem. 1983, 254, 89. (c) Patel, V. D.; Cherkas, A. A.; Nucciarone, D.; Taylor, N. J.; Carty, A. J. Organometallics, 1985,4,1792. (d) Bullock, L. M.; Field, J. S.; Haines, R. J.; Minshall, E.; Moore, M. H.; Mulla, F.; Smit, D. N.; Steer, L. M. J . Organomet. Chem. 1990, 381, 429. (e) Field, J. S.; Haines, R. J.; Mulla, F. J. Organomet. Chem. 1990,389,227. ( f )He, Z.; Jugan, N.; Neibecker, D.; Mathieu, R.; Bonnet, J. J. J. Organomet. Chem. 1992, 426,247. (g) Beguin, A.; Bottcher, H.-C.; Siiss-Fink, G.; Walther, B. J. Chem. SOC.,Dalton Trans. 1992, 2133. (22) Kwek, K. L. M. Ph.D. Thesis, University of Waterloo, 1989. (23) van Gastel, F.;Taylor, N. J.; Carty, A. J. J . Chem. SOC.,Chem. Commun. 1987, 1049. (24) van Gastel, F.; Taylor, N. J.; Carty, A. J. Inorg. Chem. 1989,28, 384. (25) Colbran, S. R.; Irele, P. T.; Johnson, B. F. G.; Lahoz, F. J.; Lewis, J.; Raithby, P. R. J. Chem. SOC.,Dalton Trans. 1989, 2023.
Cherkas et al.
1664 Inorganic Chemistry, Vol. 32, No. 9, 1993 Table I. Crystal and Intensity Data for M ~ ( C O ) I , ( ~ ~ - P(M P ~=) Ru (Za), Os (2b)) 2a
Table 11. Atomic Coordinates (X lo4) and Equivalent Isotropic Disdacement Coefficients (A2 X lo4) for R u ~ ( C O ) I ~ ( U ~ -(I) PP~)
2b
. .
temp (K) ~ ( M Ka), o cm-l transm factors R,a% R,,h %
p212121 11.03l(2) 12.366(2) 18.094(2) 2468.0( 5) 4 2.359 0.710 73 150 25.31 0.51 10-0.6423 1.54 1.77
p2 I2121 11.055(3) 12.344(3) 18.076(5) 2466.7(11) 4 3.320 0.710 73 150 206.69 0.0268-0.1 159 2.66 2.53
2.4 Hz), 131.1 (d, C ortho, 2 J =~13.0 ~ Hz), 131.0 (d, C para, 4 J p ~= 2.8 Hz), 128.4 (d, C meta, jJpc = 10.2 Hz). 'HN M R (250 MHz, CDC13, 6): 7.50-7.24 (m, CsHs). Preparation of R U ~ ( C O ) ~ ~ ( ~ ~from J - PK2[Ruq(C0)13]. P~) All manipulations were carried out in an inert-atmosphere glovebox. To a mixture of dodecacarbonyltriruthenium (1.447 g, 2.26 mmol), benzophenone (0.616 g, 3.40 mmol), and potassium (0.133 g, 3.40 mmol) was added T H F (20 mL) dropwise over a 2-h period. The solution was stirred vigorously for 24 h, yielding a deep red homogeneous solution of K ~ [ R U ~ ( C O )Dichlorophenylphosphine ~~]. (1.7 mmol, 0.231 mL) was added and the reaction mixture stirred for a further 3 h. The solvent was then removed under reduced pressure, the resultant deep red oily residue extracted into dichloromethane (7-8 mL), and the solution absorbed onto silica gel. After removal of excess solvent, the sample was placed on a 200 X 25 mm silica gel column and eluted with hexane to afford three well-separated bands. The first to elute was identified as dodecacarbonyltriruthenium followed by the major purple fraction containing R U ~ ( C O ) I ~ ( ~ (0.220 ~ - P P g, ~ )15%). The final band to be identified corresponded to Rus(C0) i5(p4-PPh),l9 identified by its familiar spectroscopic properties. X-ray Structure Analyses of 2a and 2b. Dark red crystals of 2a were grown from a dichloromethane/benzene solution at -20 "C, and those of 2b, from dichloromethane/hexane. A suitable crystal was chosen, glued to a glass fiber using epoxy resin, and mounted on a goniometer head. Unit cell parameters for each crystal were obtained from least squares refinement of the setting angles of 25 reflections well dispersed in reciprocal space. Collection and Reduction of Intensity Data. Details of the intensity data collection are given in Table I. The intensity data for both 2a and 2b were collected at 150 K on a LT2 equipped Siemens R3m/V diffractometer using graphite-monochromated Mo K a (A = 0.710 73 A) radiation and thew scan technique with a variable scan speed to optimize weak reflections. Background measurements were madeat the beginning and end of each scan, each for 25% of the total scan time. Two standard reflections monitored every 100 measurements showed no significant deviations during the data collection. Reflections were flagged as unobserved whenF< 6.0a(F) whereawasderivedfromcountingstatistics. Solution and Refinement of the Intensity Data. Patterson syntheses readily yielded the positions of all the metal atoms in both cases, and standard Fourier methods were used to locate the remaining non-hydrogen atoms in the molecule. Full-matrix least-squaresrefinement of positional and thermal parameters, subsequent conversion to anisotropic coefficients for all non-hydrogen atoms, and several further cycles of least-squares refinement followed. At thisstage, for each structurea difference Fourier map revealed the positions of all the hydrogen atoms. In subsequent refinements to convergence, the hydrogen atoms of 2a were included in calculated positions with refined isotropic thermal parameters whereas those of 2b were also included in calculated positions with fixed isotropic thermal parameters. The function minimized in the least-squares calculations was Xw(lF,I - IFcl)2.The weighted R value is defined as Rw = [Xw(lFoI- IFc/)2/CwlFol] where the weights w optimize on moderate intensities [ w ' = a2(F)]. Absorption corrections for 2a and 2b were applied by the face-indexed numerical procedure. The atomic scattering factors used including anomalous dispersion corrections were taken from
V
z
U(e.9)"
5766.6( 1) 3756.5( 1) 5218.2(1) 4728.6( 1) 5409.5(5) 8225 (2) 5306(2) 56 18(2) 2930(2) 1760(2) 2891(2) 2898(2) 7568(2) 5972(2) 5294(2) 3090(2) 6624(2) 42 12(2) 7306(2) 5459(2) 5692(2) 3264(2) 2525(2) 3231(2) 37 17(2) 6698(2) 5691(2) 52 56 (2) 3688(2) 5908(2) 4391 (2) 5631(2) 4890(2) 5 105(3) 6063(3) 6810(3) 660 1(2)
4594.0( 1) 4505.7( 1) 3226.0( 1) 4105.5(1) 4938.0(3) 4582(1) 3972(1) 6171(1) 4137(1) 4154(1) 6057( 1) 2719(1) 3574(1) 2453( 1) 1928(1) 2882(1) 3561(1) 5 196( 1) 4571(2) 4178(1) 5575(1) 4274(1) 4249(1) 5476(1) 2983(1) 3501(1) 2752(1) 2404(1) 3334(1) 3760(1) 4798(1) 5906(1) 6323(1) 7063(1) 7382(2) 6974(2) 6234(2)
154.9(4) 134.7(4) 148.1(4) 131.9(4) 137(1) 378(7) 409(7) 342(7) 352(6) 295(6) 311(6) 361(7) 283(5) 374(7) 362(6) 278(5) 312(6) 313(6) 245(6) 259(6) 221(6) 226(6) 200(6) 205(6) 234(6) 206(6) 230(6) 224(6) 193(6) 195(6) 191(5) 173(5) 222(6) 297(8) 350(9) 327(8) 259(7)
X ~~
~~
~
2698.0(2) 3841.1(2) 3976.6(2) 6054.8(2) 4673.9(5) 2600(2) 136(2) 1793(2) 1287(2) 5392(2) 3607(2) 3444(3) 4751(2) 1648(2) 5764(2) 6738( 2) 7 539( 2) 8078(2) 2603(3) 1093(3) 21 19(2) 2228(3) 4847(2) 3699(2) 3623(3) 4436(2) 2488(2) 5108(2) 6511(2) 6979(2) 7299(2) 5063(2) 5716(2) 5978(3) 5599(3) 4973(3) 4700(3)
"Equivalent isotropic U defined as one-third of the trace of the orthogonalized U,,tensor. ref 26; for hydrogen, those of Stewart et al. were used.27 All calculations were performed on a Microvax I1 using SHELXTL PLUS software. The final Rand R, values are given in Table I (2a, 53 16 observed reflections, 340 parameters refined; 2b, 3377 observed reflections, 335 parameters refined). The final difference Fourier maps exhibited minimum and maximum residuals of 0.41 and -0.39 e A-3 and 2.01 and -1.54 e k3, for 2a and 2b, respectively, in the vicinity of the metal atoms. Compounds 2a and 2b crystallize as isomorphs, in the noncentrosymmetric space group P212121. Friedel opposites in the ranges -15 Ih I 15, -17 5 k I17, and -25 i I i 25 for 2a and -17 5 h I17, -19 I k I19, and -28 II I28 for 2b were collected. In both instances, we found the correct enantiomorph (absolute structure) to be indeterminant from the merged data. However, using the unmerged Friedel pairs (2a, 9563; 2b, 5848 observed reflections), the models presented here gave R, R, values of 1.72, 1.97 and 3.04, 2.86 for 20 and 2b, respectively. The alternative enantiomorphs gave R,Rwvaules of 1.97,2.27 and 3.80,3.83 for 2a and 2b, respectively, unequivocally establishing theenantiomorphic nature of the crystal. Atomic and positional parameters (Tables I1 and 111) and an appropriate selection of bond lengths and angles (Table IV) are listed for 2a and 2b, respectively.
Results and Discussions The major impediment in developing the chemistry of Md and higher nuclearity clusters and to understanding their associated properties is the absence of rational preparative methodologies for their synthesis. The problem is further accentuated in many instances by facile cluster fragmentation, which imposes severe ~~~
~~~~
~~
~
(26) International Tables for X-ray Crystallography; Kynoch Press. Birmingham, England, 1974, Vol 4 (27) Stewart, R F , Davidson, E R., Simpson, W . T J Chem. Phys. 1965, 42, 3175
Inorganic Chemistry, Vol. 32, No. 9, 1993 1665
Transition Metal-Main Group Clusters Table 111. Atomic Coordinates (X lo4) and Equivalent Isotropic Displacement Coefficients (A2 X 10’) for O S ~ ( C O ) I J ( ~ , - P (2b) P~) X
Y
z
2718.7(4) 3889.2(4) 3969.4(5) 6084.0(4) 4711(3) 2622( 11) 188(9) 1814(9) 1357(9) 535 1(10) 3694( 10) 3366(11) 4782(9) 1664(9) 57 35( 10) 6751(9) 7572(9) 8091(9) 2633(12) 1142(15) 2133(11) 2307 (14) 4802(11) 3770( 1 1) 3562(13) 4485(13) 2488(12) 5050( 14) 6540(10) 7028(11) 7344( 12) 5097(10) 5729(11) 6027(14) 5608 ( 12) 4992(17) 47 3 6( 12)
5770.2(4) 3760.4(3) 5198.7(4) 4745.2(3) 5445(2) 8225(8) 5314(9) 5667 ( 10) 2967(8) 1752(7) 2837(7) 2867(8) 7554(7) 6009(9) 5248(9) 3106(7) 6628(9) 4187(8) 7280( 11) 5466( 11) 5727(11) 3264(10) 2520( 10) 3 195(9) 3690(12) 668 l ( l 1 ) 5697(11) 5213(11) 370 1(10) 5909( 11) 4406( 10) 5604(9) 4889( 11) 5037( 12) 6000( 15) 6758(12) 6567( 11)
461 2.1 (3) 4532.1 (2) 3226.4(2) 41 13.6(2) 4964(2) 4535(7) 3992(6) 6184(6) 4172(6) 41 11(6) 6078(5) 271 5(5) 3566(6) 2467(6) 1929(5) 2900(5) 3567(6) 5204(6) 4566(8) 421 l(7) 5590(8) 4325(7) 4257(7) 5492(7) 2939(7) 3488(7) 2762(7) 2400(7) 3326(7) 3763 (7) 4804(8) 5957(6) 6350(6) 7089(7) 7416(8) 7014(8) 6283(7)
Equivalent isotropic U defined as one-third of the trace of the orthogonalized Ut, tensor.
restrictions upon the reaction conditions employed to initiate reactions. There is considerable interest in the butterfly class of tetranuclear clusters displayinga nonplanar arrangement of metal atoms.lOJ1 Such clusters often bear small molecules or main group atoms within the cavity between the wing tip atoms and exhibitunusual reactivitypatterns?8 Theintracavity coordination environment of butterfly clusters is flexible and facilitates smallmolecule activation throughm~ltisitecoordination.2~ We recently established an extensive manifold of chemistry for the phosphinidene-stabilized butterfly cluster nido-Rur(C0) I&-PPh) (2a), containing a butterfly configuration of metal atoms, and reported a remarkably facile activationof dihydrogenby 2a, which occurs upon UV irradiation under ambient condition^.^^ We have also noted that the arrangement of metal atoms in this skeletal (28) (a) Dahl, L. F.; Smith, D. L. J. Am. Chem. SOC.1962,84, 2450. (b) Gervasio, G.; Rossetti, R.; Stanghellini, P. L. Organometallics 1985,4, W.;Stevenson, 1612. (c)Rumin,R.;Robin,F.;Petillon,F.Y.;Muir,K. I. Organometallics 1991,10,2274. (d) Sappa, E.;Belletti,D.;Tiripicchio, A,; Tiripicchio-Camellini,M. J. Orgunomet. Chem. 1989,359,419. ( e ) Lentz, D.; Micheal, H. Angew. Chem., Int. Ed. Engl. 1988, 100, 871. (f) Albiez, T.; Powell, A. K.; Vahrenkamp, H. Chem. Ber. 1990, 123, 667. (9) Bantel, H.; Powell, A. K.; Vahrenkamp, H. Chem. Ber. 1990, I23,661. (h) Collins, M. A.; Johnson, B. F. G.; Lewis, L.; Mace, J. M.; Morris, J.; McPartlin, M.; Nelson, W. J. H.; Puga, J.; Raithby, P. R. J. Chem.Soc., Chem. Commun. 1983,689. (i) Blohm, M. L.;Gladfelter, W. L. Organometallics 1985, 4, 45. (i)Cowie, A. G.; Johnson, B. F. G.; Lewis, J.; Raithby, P. R. J . Organomet. Chem. 1988,306, C63. (k) Holt, E. M.; Whitmire,K. H.;Shriver,D. F. J. Organomet. Chem. 1981, 213, 125. (1) Adams, R. D.; Babin, J. E.; Tanner, J. T. Organometallics 1988, 7 , 765. (29) (a) Horwitz, C. P.; Shriver, D. F. Adu. Organomet. Chem. 1984, 23, 219. (b) Shriver, D. F.; Sailor, M. J. Acc. Chem. Res. 1988, 21, 374. (30) van Gastel, F.; Corrigan, J. F.; Doherty, S.; Taylor, N. J.; Carty, A. J. Inorg. Chem. 1992, 31, 4492.
Table IV. Selected Interatomic Bond Distances (A) and Angles (deg) for M4(CO)&’-PPh) (M = Ru (2a), Os (2b)) bond dist/angle M(1 )-M(2) M( 1) - ~ ( 3 ) ~ ( 2 1 ~ 3 ) M(2)-M(4) M(3)-M(4) M ( 1)-P( 11 M(2)-P(1) ~(4)-~(1) M(2)-M( 1)-M(3) M( l)-M(2)-M(4) M( l)-M(2)-M(3) M(3)-M(2)-M(4) M( l)-M(3)-M(2) M( 1)-M(3)-M(4) M(2)-M(3)-M(4) M(2)-M(4)-M(3) M(3)-M( 1)-P(l) M( l)-M(Z)-P( 1) M(3)-M(2)-P( 1) M(4)-M(2)-P(l) M (2)-M (4)-P( 1) M(3)-M(4)-P( 1) M(1)-P(1)-M(2) M( 1)-P( 1)-M(4) M (2)-P( 1)-M (4) P(l)-M(l )-C(1) P( l)-M(l)-C(2) P(l)-M( 1)-C(3) ~(1)-~(2)-~(4) P( 1)-M(2)-C( 5) P(l)-M(2)-C(6) P(l)-M(4)-C(ll) P( 1)-M(4)-C( 12) P(l)-M(4)
